Freelance cameraman Charlie Johnson believes he filmed the raunchy online video in the historic cinema, in High Road, East Finchley, around seven years ago and that his employer, the website Purecfnm, would have been open about its intentions when hiring the venue.

This week, barrister James Kessler, deputy chair of the Phoenix Cinema Trust, which owns the venue, told the Ham&High he did not believe the film was part of a professional porn shoot but rather a hen night party turned raunchy. He refused to make any further comment.

But Mr Johnson did not believe the cinema had been unaware of the porn shoot taking place in its auditorium.

“I’m sure they would have been made aware [of the nature of the shoot],” he said. “We are normally very careful not to film anything which identifies the set. It’s not unusual for a film to be shot in a cinema.”

Last Thursday, the Ham&High revealed the seven-minute adult film shot in the Phoenix had been widely circulated on the internet via the Xvideos website.

The film features a group of six women sat on the Phoenix’s distinctive red seats cheering on another woman as she performs an explicit sex act on a naked man.

The film is being hyped as part of the CFNM genre of erotica, which stands for “clothed female, naked male”.

Mr Johnson, who has shot more than 2,000 adults films, as well as directing his own scenes, said the film was originally shot for Purecfnm’s “private members’ website” and had been “pirated” by video-sharing site Xvideos.

“Legally only the people who pay membership fees for Purecfnm should be able to see it,” he added.

The Phoenix, which celebrated its centenary year in 2012, is London’s oldest continuously-running cinema and is available to hire for film shoots, charity functions and private parties.

But the cinema’s executive director Elizabeth Taylor-Mead insisted the venue would “never ever knowingly allow a hire for a pornographic film”.

It has a number of high-profile patrons, including actress Maureen Lipman, comedian Victoria Wood, Monty Python star Michael Palin and film critic Mark Kermode.

Ms Lipman insisted she would not be getting her “knickers in a twist” about the film, adding: “I hope the Phoenix was looking majestic. I’d like to know which seat this went on in, because I don’t want to sit there.”

A controversial proposal to build an 11-storey residential tower in the heart of West Hampstead will be considered by Camden Council tonight – as the lone Labour councillor vocally opposing the plans is criticised by colleagues and branded “misguided”.